Pump prices can be off by a shot
| • | Old gas-pricing formula continues |
By Sean Hao
Advertiser Staff Writer
The practice of pricing gasoline in fractions of a cent is an everyday oddity.
Photos by Richard Ambo • The Honolulu Advertiser
Bread doesn't sell for $2.259 a loaf. Milk isn't sold for $5.759 a gallon. But when it comes to gasoline, few balk at paying $2.459 a gallon. It's a long-standing practice that implies a level of accuracy that's difficult to achieve and isn't required by law.
The state inspects gas pumps once every three years using these calibrated gasoline measurement tanks. Most pumps were found to meet the state's requirement for accuracy although among those that fail, it is not known if too much or too little gasoline was dispensed.
While gasoline pumps are highly accurate, they're not perfect.
The real value of a transaction can vary by about two cents a gallon, or 20 cents on a 10-gallon purchase, and still be within legal requirements.
The fact that gasoline pumps may not be as accurate as their readouts seem to indicate, didn't surprise Cort Haverly, a real-estate consultant who works in Honolulu. "I don't think any of that stuff is all that accurate."
The state sends inspectors to test gasoline pumps about once every three years. What they have found is most pumps meet the state's requirement for accuracy and among those that do not, more often they favor the customer, according to state officials.
"These pumps are just so accurate," said Bill Green, a former owner and now consultant to the Kahala Shell gasoline station. "I just see no problem with it at all."
Under state law, pumps can be off by up to half a percent, or about half a shot glass of gasoline, per gallon. For newly installed pumps, the tolerance for error is lower. While that may not sound like much, at today's prices, that small amount of gasoline is worth about a penny, or a nickel's worth of gasoline per 5 gallons.
Such differences can work for or against consumers. But dealers, fearing liability, typically err in favor of consumers, according to state officials and station management.
State officials inspected 1,217 pumps, or 14 percent of all pumps, in the fiscal year ended June 30, 2004, and found only 6.8 percent failed the accuracy test, according to figures recently released by the Department of Agriculture.
The year before, when about 71 percent of all pumps were inspected, one in four pumps statewide were out of tolerance by more than the allowed 0.5 percent deviation.
Photos by Richard Ambo • The Honolulu Advertiser
The state does not track whether pumps that fail inspection were dispensing too much or too little gasoline, however, Bill Pierpont, chief of the state Measurement Standards Branch, said pumps typically err in favor of consumers.
State Measurement Standards Branch specialist Wendell Murakami checks the tank gauge, which has graduations down to the cubic inch.
One reason the state allows pumps to be off by 0.5 percent is the effect of temperature on fuel. Gasoline will contract when cold and expand when hot.
Gasoline pumps in Hawai'i are calibrated to deliver exactly one gallon at a temperature of 80 degrees Fahrenheit. However, a gallon of gasoline sold at 10 degrees above or below that temperature can differ in volume by about a shot glass, or nearly 2 cents, a gallon. Consumers still get the same volume of gasoline, just more or less energy per gallon, depending on the temperature of gasoline purchased.
"As the fuel gets warmer physically the volume is increasing, but the amount of energy remains the same," Pierpont said. "So you're buying less energy for the same price. Over a year, that adds up.
"Buying gasoline in the morning before the sun comes up is probably the best time to buy fuel in Hawai'i," Pierpont said.
While the amount of gasoline pumped into your car may be off by a few cents, sales of tanker loads of gasoline to stations are "deadly accurate," Pierpont said. Technology is used to adjust for temperature differences when tanker loads are sold. But not with consumer transactions, which are small and have less impact.
The effect of temperature on consumer gasoline purchases should balance out over time, Kahala Shell's Green said.
Reach Sean Hao at shao@honoluluadvertiser.com or 525-8093.
• • •
80 degrees 0.5 percent Gasoline-pump accuracy If you go out of your way to find gas selling for two cents a gallon less than the nearest station, you may be in for a surprise. The state tests retail gasoline pumps for accuracy but tolerates a small difference between what you see on the pump and what you get. The state allows pumps to be off by 0.5 percent (up or down) in a 5-gallon test at 80 degrees Fahrenheit. Why you should fill it up early Consumers typically buy gasoline in the afternoon after work. But because the volume of gasoline expands as temperatures rise, you actually get less energy per gallon when the temperature of gasoline is above 80 degrees Fahrenheit. As a result, the best time to buy gasoline is in the morning before temperatures begin to rise. Gasoline sold at a temperature of 90 degrees Fahrenheit occupies about 0.5 percent more volume than gasoline sold at 80 degrees Fahrenheit. Consumers still get the same volume of gasoline, just less energy per gallon when the temperature is higher.
2 cents
Amount a transaction can vary per gallon
Gas-pump calibration temperature
Allowable error under state law
